On 14 June 2010, the Irish Independent reported that in 2006, O'Brien spent millions of euro on agricultural land outside the village of Inniskeen, County Monaghan in the hope that it would be rezoned for housing. However, the Inniskeen Action Committee opposed the development and, despite several Fianna Fáil councillors voting for the rezoning, the motion was defeated by Fine Gael and Sinn Féin councillors. The land is now worth a fraction of the purchase price.
O'Brien did not contest the 2011 Seanad election. In November 2013, he was sentenced to two years' imprisonment and a further year suspended, after pleading guilty with two other men to a charge of demanding €100,000 with menaces from Michael Heelan at Carrickmacross on 27 April 2012.